3D Printer

ABSTRACT

A method for forming an object having a three-dimensional target shape, that makes use of a build powder, a support powder and a binder. The build powder is more strongly bound by the binder than is the support powder. The build powder and the support powder are dispensed in a sequence of layers of build powder patterned with support powder that collectively form the three-dimensional shape in build powder, and the binder is applied to the deposited build powder, thereby forming the object of build powder and binder. Finally, the formed object is separated from the support powder.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/889,664, filed Feb. 6, 2018, which itself is a continuation ofinternational application PCT/US17/52593 filed on Sep. 20, 2017, whichclaims benefit of provisional application U.S. Ser. No. 62/397,549,filed on Sep. 21, 2016, all of which are incorporated by reference as iffully set forth herein.

TECHNICAL FIELD

The present invention is in the field of 3D printers for the manufactureof objects.

BACKGROUND ART

Although three-dimensional (3D) printing does currently exist, much ofthis technology is expensive to use, and the range of materials that areuseable in a particular printer are usually quite limited. This createsan encumbrance, especially for those wishing to produce metal partsthrough 3D printing.

One example is US Published Application No. 2015/0210010, in whichliquid or gel substances are deposited and then cured. The use ofliquids and gels limits material selection. For example, it isimpractical to dispense most metals as liquids because of their highmelting temperatures, and tendency to oxidize when molten and exposed toair. Also, US Published Application No. 2002/0145213, discloses thedeposition of layers of build powder, and the selective deposition ofbinder powder interspersed into the build powder. But using this method,it is virtually impossible to get the thorough mixture of bind powderwith build powder that is necessary to create a uniform printed object,without porosities. Further, if the build and binder powders aresimilar, the unbound build powder may tend to sinter together at thetemperatures necessary to activate the bind powder, causing greatdifficulty in freeing the printed object from the surrounding sinteredpowder. But if the bind powder and build powder are dissimilar, thedifferent material qualities can cause undesirable properties in theresultant 3D printed object. Both of these references appear to disclosesystems in which a curing operation is required after the deposition ofeach layer, a step that prolongs the process and adds to the complexityand expense of the required machinery.

SUMMARY

In a first separate aspect, the present invention may take the form of amethod for forming an object having a three-dimensional target shape,that makes use of a build powder, a support powder and a binder. Thebuild powder is more strongly bound by the binder than is the supportpowder. The build powder and the support powder are dispensed in asequence of layers of build powder patterned with support powder thatcollectively form the three-dimensional shape in build powder, and thebinder is applied to layers of build and support powder and permitted tocure, thereby forming the object of build powder and binder. Finally,the support powder is removed from the formed object.

In a second separate aspect, the present invention may take the form ofan apparatus for making three-dimensional physical objects, thatincludes a frame and a pan. A build powder pourer is at least partiallyfilled with build powder and a support powder pourer is at leastpartially filled with support powder, each of the pourers having adispensing opening and a dispensing plug, controllably covering thedispensing opening. A pourer-movement and dispensing plug-actuatingassembly is supported by the frame over the pan, and includes a movementelement that is selectively attachable to the build powder pourer andalternately to the support powder pourer and is also capable tocontrollably move an attached pourer in three orthogonal dimensions andto control the dispensing plug. A computer assembly, including an inputfor receiving a target three-dimensional shape, controls thepourer-movement and dispensing plug-actuating assembly to move thepourers and selectively open the plugs, thereby causing powder to bepoured into the pan, and to thereby create in the pan a sequence oflayers of build powder patterned with support powder that collectivelyforms the target shape in build powder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1.1, 1.2 and 1.3 are perspective views of a 3D printer accordingto one embodiment of the present invention, as viewed from threedifferent angles.

FIGS. 2.1, 2.2 and 2.3 are detail views of a 3D printer fork, which is acomponent of the 3D printer of FIG. 1.1.

FIGS. 3.1, 3.2, and 3.3 are detail views of a 3D printer pourer, whichis a component of the printer of FIG. 1.1, as viewed from threedifferent angles.

FIGS. 3.4 and 3.5 are cross-sectional detail views of the 3D printerpourer of FIG. 3.1.

FIGS. 4.1, 4.2 and 4.3 are detail views of the 3D printer fork assemblyof FIG. 2.1 holding the pourer of FIG. 3.1.

FIG. 5.1 is a cross-sectional view of the 3D printer pourer of FIG. 3.1,showing the plug rod in a raised position.

FIG. 5.2 is a cross-sectional view of a 3D printer pourer of FIG. 3.1,showing the plug rod in a raised position.

FIGS. 6.1 and 6.2 are detail views of a 3D printer refill assembly, thatforms a part of the 3D printer of FIG. 1.1, as viewed from two differentangles.

FIG. 7.1 is a cross-sectional detail view of the 3D printer refillassembly of FIG. 6.1, without a pourer present.

FIG. 7.2 is a cross-sectional detail view of the 3D printer refillassembly of FIG. 6.1, with a pourer present.

FIG. 8A-8D show the pan in the process of being filled and covered,prior to being placed into a kiln.

FIG. 9A is a front-top-side isometric view of an alternative embodimentof a 3D printer.

FIG. 9B is a front-bottom-side isometric view of the 3D printer of FIG.9A.

FIG. 10A is a front-top-side isometric view of the printer of FIG. 9A,with frame elements removed to provide a clearer view of the innerworkings.

FIG. 10B is front-top-side isometric view of the printer portions ofFIG. 10A, at a less steep angle of view.

FIG. 11A is a front-top-side isometric view of a fork assembly, whichforms a part of the printer of FIG. 9A.

FIG. 11B rear-top-side isometric view of the fork assembly of FIG. 11A.

FIG. 11C is a side view of the fork assembly of FIG. 11A.

FIG. 12A is a side view of the fork assembly of FIG. 11A and a pourerthat forms a part of the printer of FIG. 9A, joined together.

FIG. 12B is a rear-top-side isometric view of the combination of partsshown in FIG. 12A.

FIG. 13A is a top angle isometric view of a pourer, that forms a part ofthe printer of 9A.

FIG. 13B, is a section view of the pourer of FIG. 13A.

FIG. 13C, is a bottom angle isometric view of the pourer of FIG. 13A.

FIG. 14A is a top angle isometric view of an alternative embodiment of apourer, that forms a part of the printer of 9A.

FIG. 14B, is a section view of the pourer of FIG. 14A.

FIG. 14C, is a bottom angle isometric view of the pourer of FIG. 14A.

FIG. 15A is an isometric view of a docking station for a pourer, thatforms part of the printer of FIG. 9A.

FIG. 15B is a sectional view of the docking station of FIG. 15A.

FIG. 16A is an isometric sectional view of a docking station with apourer attached, that collectively form part of the printer of FIG. 9A.

FIG. 16B is a side sectional view of the docking station and pourer ofFIG. 16A.

FIG. 17A is a block diagram of the printer of FIG. 9A.

BEST MODES OF CARRYING OUT THE INVENTION

Definition: the term, “metal” is used in this application, encompassesmetal alloys.

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

Note: where there are a set of like elements, labelled N.1-N.4 (where Nis an integer), an arbitrary one of these will be labelled, for exampleN, where it does not matter which one of N.1-N.4 is being referred to.For example, if an arbitrary one of pourers 10.1-10.4 is being referredto, it will be referenced by “10”.

FIGS. 1.1, 1.2 and 1.3 show a 3D printer from various angles. The 3Dprinter 8 is made up primarily of a pan 4 (also referred to as acontainer), a set of pourers 10.1-10.4, each of which is associated witha docking station 30.1-30.4, where the pourer 10 can be refilled by anassociated refill tank 11. Also, a rigid frame 3 supports the dockingstations 30.1-30.4 and a pourer movement assembly 116 (FIG. 10A).Assembly 116 includes a fork assembly 5 (which may also be referred toas a “movement element”) that attaches to a selected pourer 10, removespourer 10 from a docking station 30, and moves pourer 10 through apattern as fork assembly 5 actuates pourer 10, to selectively dispensepowder (by way of pourer plug rod 19, discussed below). When present onassembly 5, pourer 10 rests on fork 6. Accordingly, pourer-movementassembly 116, may also be termed a pourer-movement and dispensingplug-actuating assembly 116.

The 3D printer uses a build powder and a support powder to build up 3Dobjects in the pan 4, layer by layer. Each layer consists of a region ormultiple regions filled with build powder while the rest of the pan areain that layer is filled with support powder. In one embodiment, somepart of a region might be skipped during pouring of a layer and filledlater when pouring a layer above it, to increase the speed of thepouring process. After all layers have been poured, the build powder isbound by a binder, resulting in a 3D object, which is then separatedfrom the support powder. The powders may be made from any appropriatematerial, provided that the following requirements are met:

1. Build and support powders are pourable, or at least arrangeable intoa desired pattern by an appropriate mechanism.2. Build powder is strongly bindable by the binder.3. Support powder is far less strongly bindable by the binder that isthe build powder.4. Build and support powders remain mostly in solid particulate formduring the process, to prevent shape distortion.It is also important that the ambient gas is chosen appropriately tofacilitate the above requirements. For example, if oxidation wouldnegatively impact bindability of the build powder by the binder, theambient gas should be selected to prevent oxidation. For example, insome embodiments the ambient gas is argon. In these embodiments themechanism is enclosed in an air-tight chamber. In an alternativeembodiment a substance that binds with oxygen, such as carbon in theform of coke, is put in the pan 4 before it is heated

In a preferred embodiment, iron powder is used as the build powder,silicon dioxide powder is used as the support powder, and molteniron-carbon alloy with high carbon content is used as a binder.Iron-carbon alloys of varying carbon content may be used, although acarbon content of 4.3% has the advantage of having the lowest meltingtemperature—about 1147 degrees Celsius. This alloy is commonly availableas “Pig Iron,” and is henceforth referred to simply as “Pig” in thistext. In this embodiment, the powders are poured in such a way that thetop layer has exposed build powder.

After the 3D pattern of iron powder and SiO₂ powder has been created, aseparator 110, having a through-hole is placed over the powder and apiece of Pig and a piece of carbon, such as coke, are placed on theseparator, in such manner to avoid deforming the build powder shape. Thepig should cover the hole in the separator 110, which should be abovethe surface of exposed build powder, to avoid SiO₂ powder blocking theflow of molten pig. The pan 4 is then filled the rest of the way withSiO₂ powder (in some methods, sand). The piece of carbon is needed toconvert oxygen into carbon monoxide when heated, to prevent oxidation ofthe iron. The pan 4 is closed with a lid, transferred to a kiln, andheated. The kiln temperature is chosen to be above the meltingtemperature of Pig but below the melting temperature of the iron powder.When the temperature gets high enough, the Pig melts and soaks throughthe iron powder by capillary action, but the Pig does not soak thesilicon dioxide powder, which resists wetting by molten iron. The pan isheld at that temperature for a certain length of time, referred to asthe hold time. During the hold time, the carbon atoms of the molten Pigdiffuse into the particles of the iron powder, thus equalizing thecarbon content. Longer hold times result in a better diffusion. Afterthe pan is cooled down, the printed object is separated from the supportpowder and the remains of the Pig are cut off. Preferably, the printedobject is designed such that it has an additional narrow neck at the topand a flat pad above it, such that the molten Pig would soak the objectthrough the pad and the neck, making it easier to cut or break the neckseparating the object from the pad and the remains of the Pig. Theresulting material of the printed object is carbon steel. Furtherpost-processing and heat treatment can be used to achieve desiredproperties and dimensions.

In another embodiment, the build powder is copper powder, the supportpowder is silicon dioxide, and the binder is copper-silver alloy.

In additional embodiments, instead of using a molten material as thebinder, a chemical process is used to bind the particles of the buildpowder.

In one embodiment, the build powder is cement, the support powder issilicon dioxide, and the binder is water, which soaks the cement andcauses binding.

In another embodiment, an epoxy is used as the binder. The build powderis a polymer such as, for example, Polytetrafluoroethylene (PTFE),Polyether ether ketone (PEEK), Nylon, Acrylonitrile Butadiene Styrene(ABS), Polylactic Acid (PLA), Polyoxymethylene (POM), Polycarbonate(PC), Polyvinyl Chloride (PVC), Polyethylene terephthalate (PET),Polyethylene (PE), Polypropylene (PP), Polystyrene (PS), Poly(methylmethacrylate) (PMMA), Polybenzimidazole (PBI), Polyethersulfone (PES),Polyetherimide (PEI), Polyphenylene oxide (PPO), or Polyphenylenesulfide (PPS), and the support powder is another polymer from the samelist. The polymer used for support powder is non-wettable by the epoxy;the polymer used for build powder is wettable by the epoxy.

In another embodiment, a glue is used as the binder instead of epoxy.The glue can be either chemical or thermal.

In another embodiment, heat is used to bind the particles of the buildpowder. The build powder is selected to have a glass transitiontemperature that is lower than the glass transition temperature of thesupport powder. The temperature used for binding is chosen to be abovethe glass transition temperature of the build powder and sufficient tostrongly bind the build powder particles together, but not high enoughto strongly bind the support powder particles, so that the support canbe separated from the object without breaking it. The temperatureselected should be below the melting point of either of the two powdersto prevent shape distortion.

In another embodiment, multiple build powders of different colors areused to create colorful objects.

Referring again to FIGS. 1.1, 1.2 and 1.3, a pourer-movement assembly116 includes stepper motors 1.X, 1.Y, 1.Z, which rotate lead screws 2.X,2.Y, 2.Z to move the fork assembly 5, holding a pourer 10, in threedimensions along the X, Y and Z axes, respectively.

FIGS. 2.1, 2.2 and 2.3 show details of the fork assembly 5. The forkassembly 5 can hold any one of the four pourers 10, which are identicalinsofar as the portions that contact the fork assembly 5.

FIGS. 3.1, 3.2, 3.3, 3.4 and 3.5 show details of a pourer 10.

FIGS. 4.1, 4.2 and 4.3 show the fork assembly 5 (which may also bereferred to as a movement element, as it holds and moves a pourer 10).

Referring now to FIGS. 2.1 to 2.3, fork assembly 5 has a pour plugactuating stepper motor 1.P that rotates lead screw 2.P and moves apourer control carriage 15, vertically. As carriage 15 moves down,referring now to 3.1, which shows the top of a pourer 10, which forpurposes of this discussion is engaged with fork assembly 5, it pushesand tilts seesaw 16 via spring 17 (FIG. 2.3). As seesaw 16 tilts itpushes ball bearing 18 up, thus lifting pourer plug rod 19 (FIG. 3.4),so that the end of rod 19 no longer plugs pourer hole 20, therebypermitting powder to flow from hole 20. As the end of plug rod 19 plugspourer hole 20, this end may be termed a “plug.”

Fork assembly 5 also includes plug rod rotating stepper motor 1.S thatrotates a claw 21. When carriage 15 is lowered, claw 21 engages with androtates knob 22 (FIG. 3.1). Referring to FIG. 3.5, knob 22 is connectedvia axle 23 and coupler 24 to pourer plug rod 19. Axle 23 is heldhorizontally by another two ball bearings (not shown) inside bridge 26but can freely rotate and slide vertically. Spring 25 increases closingforce of plug rod 19.

FIGS. 5.1 and 5.2 show that plug rod 19 is slightly bent, so when therod moves up, the bottom end of the rod also moves sideways, such thatwhen rod 19 rotates it stirs the powder, thus increasing the flow rateand consistency. Rod 19 is also flexible, so when it moves down theslope of the bottom guides its tip to slide to the center of the pourerand into hole 20, sealing the opening.

In one embodiment, there are four pourers: two for support powder andtwo for build powder. Of the two pourers for each type of powder, onehas a smaller hole 20 for higher resolution pouring, and one has alarger hole 20 for faster pouring.

FIGS. 6.1, 6.2, 7.1 and 7.2 show the pourer refill mechanism. Eachpourer 10.1-10.4, is refilled from its own refill tank 11.1-11.4,respectively. Refill tank 11.1-11.4 is connected by pipe 12 to injectorchamber 13. As shown in detail in FIG. 7.2, the injector chamber has ahole 35 in the bottom, which serves as a refill opening, and which isclosed by plug 14, which serves as a refill plug. Geared stepper motor31 winds and unwinds cable 32 thus tilting refill assembly on hinge 33.As the refill assembly is tilted the injector chamber moves vertically.When a pourer 10.1-10.4 is engaged with its docking station 30.1-30.4,and the injector chamber is lowered, rod 34 of the pourer pushesinjector plug rod 14 up, thus opening hole 35 and allowing the powder toflow from the refill tank into the pourer. When the injector chamber islifted, or pourer 10.1-10.4 is absent, rod 14 moves down closing hole35.

Referring to FIG. 17A, before the printing process begins, astereolithography (STL) file 162 is loaded into a computer 160, whichexecutes a computer program that loaded from non-transitory computerreadable memory, commonly referred to as a slicer program, thattranslates the STL file into G-code, a form of motion commands that canbe understood by a controller board 161. Controller board 161 creates aset of signals that control motors 1.x, 1.y, 1.z, 1.p and 151, throughthe printing process. At the beginning of this process, fork assembly 5retrieves a desired pourer 10 from the docking station 30 and positionsit in the desired location over pan 4. Stepper motor 1.P opens thethrough-hole 20 (as described above) allowing the powder to flow intothe pan. As the powder pours from through-hole 20, stepper motors 1.Xand 1.Y are controlled by controller board 161 to move the fork assembly5 in and X, Y pattern, creating a desired pattern of either build powderor support powder. Then stepper motor 1.P closes hole 20, shutting offthe flow of powder, and returns the pourer to the refill docking station30. Fork assembly 5 then retrieves a different pourer 10, and so on,until the pan is filled as desired.

FIGS. 9A through 16B show an alternative embodiment 108 to that ofprinter 8. Embodiment 108 includes docking stations 140 and a forkassembly 105 that have some significant differences from dockingstations 30 and fork assembly 5. In broad overview, docking stations 140do not include a motor. Rather, the refilling operation is actuated by asequence of movements of the fork assembly, as will be explainedfurther, below. Also, fork assembly 105 uses a DC motor 151, rather thanthe stepper motor 1.p, to raise and lower the pourer plug rod 19. In onemore difference, printer 108 is equipped with adjustable length legs130, so that it can be placed over a kiln base 131. In one method ofuse, printer 108 is lifted away after laying down the build and supportpowder, and the rest of the kiln is placed on the kiln base 131, tocomplete the kiln, so that pan 4 and its contents can be heated inplace.

Referring first to FIGS. 15A, 15B and 16A, each docking station 140defines a powder passageway 142, leading to a powder pour spout 143.Station 140 further includes support balls 163 (only one shown).Additionally, a rocker arm 141, is hinged to station 140, and has a pairof teeth 145 and a plug 146. A spring urges rocker arm 141 into a powderflow blocking position, where plug 146 is interposed between passageway142 and pour spout 143. When the computer 160 determines that a pourer10 will be docked, it commands motors 1.x, 1.y and 1.z to move thepourer 10 to a position in which a portion of the top of pourer 10 isdirectly beneath the teeth 145, and then pushes pourer 10 upwardly tolift teeth 145 and thereby move rocker arm 141 into a powder dispensingposition, where plug 146 is lifted from the top of pour spout 143.Pourer is then moved further into contact with docking station 140 sothat the lip 148 of the pourer 10 rests on the support balls 163 andteeth 145 contact the top surface of pourer 10, which thereby maintainsteeth in a raised position, which maintains plug 146 in positioned thatis not plugging pour spout 143. Finally, a pair of indents 170 (FIG.13C) on the bottom of lip 148 engaged to a pair of support balls 163(FIG. 15A) to retain it as it is released by fork assembly 105, bylowering fork assembly 105 and moving it away from pourer 10 when pourer10 no longer rests on it. This design has the advantage of illuminatingfour electric motors, thereby reducing cost, complexity and potentialmaintenance expense.

Referring to FIG. 12A, actuating arm 150, which is hinged to the forkassembly 105 at hinge 149, includes a downwardly extending push panel156. When arm 150 is lowered, it presses down against pourer rocker arm16 (FIG. 13A), which lifts up on ball bearing 18, in turn lifting pourerplug rod 19, permitting powder to flow out. When arm 150 returns to itsraised position, pourer plug rod 19 is urged downwardly by spring 25,stopping the flow of powder, with hinged arm 16 and ball bearing 18 alsoreturning to non-dispensing positions. There are some differencesbetween the pourer 10, shown in FIGS. 13A-13C, and that shown in FIGS.14A-14C. Hole 20 is smaller in that shown in FIGS. 13A-13C, for layingdown a finer line of powder. Similar to the case for printer 8, whenpourer 10 is on fork assembly 105, it rests on fork 106.

The above noted movement of arm 150 is effected by a DC Motor 151 (FIG.12B), which turns spool 154, pulling or releasing a steel cable 155 thatis engaged with pulley 157 and anchored at a switch 152. Starting witharm 150 in its down position, push panel 156 rests on rocker arm 16, sothat there is little tension in cable 155, which has placed switch 152,in its cable slack position. When it is required to stop dispensingpowder, DC motor 151 turns spool 154 to reel in cable 155, therebycausing switch 152 to switch to its cable tense position (a transitionthat does not affect operation) and for cable to pull up on pulley 157,thereby pulling up on arm 150 which continues to rise until it contactsanother switch (not shown) located along the path of arm 150, whichcreates a signal that stops the process. DC motor 151 maintains itsposition by the friction of an internal gear assembly and arm 150 staysin the same position until it is time to move arm 150 and dispensepowder. When this action is required, DC motor 151, turns spool 154 soas to spool out cable 155, causing arm 150 to drop until panel 156 isresting on arm 16. At this point cable 155 goes slack enough so thatswitch 152 transitions to a cable slack position, which is perceived bycomputer 160, or in an alternative embodiment, just by controller board161, causing the process to stop, with the DC motor again stopped inplace.

The fork assembly 105, rides vertically on a vertical tube 186 (FIG.10B), which extends through partially enclosed space 188, with a pair ofupper ball bearings 182 and lower ball bearings 184 smoothing the ride.Vertical tube 186 rides on a carriage 190, that is moved side-to-side ontubes 192 and forward and backward on tubes 194 (FIG. 10B). Tubes 192and 194 provide a light weight but rigid framework for movement ofcarriage 190, and thereby fork assembly 105, which also moves on tube186. As noted elsewhere, this movement is powered by motors 1.X, 1.Y and1.Z.

Example 1

In one example the following parameters were used to produce a highcarbon steel 3D printed object.

Build powder: IRON100

The specification, and ordering information for IRON100 can be found onthe Internet at:http://www.iron-powder.com/wp-content/uploads/2014/03/IRON100_Specifications.pdf

Following is some information concerning IRON100:

Chemical Analysis (by Weight)

Fe 99.5%+

O 0.200%

C 0.030%

Si 0.030%

Flow rate 29.00 sec/50 g

Particle size <212 microns.

Median particle size: 100 microns.

Support Powder: OK85

The specification for OK85, a product of USSilica, can be found at thefollowing Internet address, and is also reproduced below.

http://www.ussilica.com/sites/ussilica.com/uploads/files/product-data-sheets/industry/foundry/OK85.pdf

Grain Shape: Round

Melting Point: 3100 Degrees F.

Mineral: Quartz

Typical Chemical Analysis: SiO₂ (Silicon Dioxide) 99.8%

Particle size: <425 microns.

Median particle size: 150 microns.

Sorelmetal Grade RF1

Carbon Silicon Manganese Phosphorus Sulfur 4.25% 0.15% 0.022% 0.033%0.013%

Available in an Ingot Size (Approx):

185×120×55 mm (7.25″×4.7×2.5)

Weight (Approx.):

5.54 kb (12 lbs.)

Pourer hole diameter: 1 mm for the smaller hole and 4 mm for the biggerhole.Pourer horizontal moving speed while pouring (in millimeters persecond):

Build: 2 Support: 8 Kiln Settings:

Ramp: 600 degrees Celsius per hourHold temperature: 1250 degrees CelsiusHold time: 4 hours

Example 2

In another example similar parameters were used, except the following:

The OK85 powder was filtered to remove 25% of the largest and 5% of thesmallest particles.The IRON100 powder was filtered to remove 20% of the smallest particles.Pourer hole diameter: 1 mm for the smaller hole and 2 mm for the biggerhole.Pourer horizontal moving speed while pouring (in millimeters persecond):

Build: 16 Support: 20

Kiln settings:Ramp: 600 degrees Celsius per hourHold temperature: 1180 degrees CelsiusHold time: 2 hours

Referring, now, to FIGS. 8A through 8D, after the process of filling pan4 with build and support powder by the 3D printer is complete, a shelf110, having an opening and being shaped to encourage liquid flow throughthe opening, is placed on top of this powder. A piece of pig 111 and apiece of coke 112 are placed on top shelf 110, and a lid 113 is placedover all of this. An inert particulate material, such as sand is thenpoured through a hole 114 in lid 113. This prevents shelf from ridingup, and aids shelf in keeping the SiO₂ powder tightly packed, therebypreventing the molten pig from lifting the SiO₂.

INDUSTRIAL APPLICABILITY

The present invention finds industrial applicability in the manufactureof objects via 3D printing.

While a number of exemplary aspects and embodiments have been discussedabove, those possessed of skill in the art will recognize certainmodifications, permutations, additions and sub-combinations thereof. Itis therefore intended that the following appended claims and claimshereafter introduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

1. A method for forming an object having a three-dimensional targetshape, comprising: a) providing a build powder, a support powder, abinder and a container and wherein said build powder is bindable by saidbinder and said support powder is substantially not bindable by saidbinder; b) dispensing said build powder and said support powder intosaid container in a sequence of layers of build powder patterned withsupport powder that collectively form the three-dimensional shape inbuild powder, supported directly by support powder; c) applying thebinder to the build powder, thereby forming said object, made of buildpowder and binder; and; d) separating said object from said supportpowder.
 2. The method of claim 1, wherein the build powder and thesupport powder are pourable.
 3. The method of claim 1, wherein thebinder is a liquid and the build powder is wettable by the binder andthe support powder is not wettable by the binder.
 4. The method of claim1, wherein the build powder and the support powder remain substantiallyas solid particles when the binder is applied.
 5. The method of claim 1,wherein the binder is heated to activate the binding properties of thebinder.
 6. The method of claim 1, wherein the build powder is a metalpowder and the binder is a molten metal.
 7. The method of claim 1,wherein the build powder is a metal powder and the binder is a metal,and wherein the binder is applied in solid particle form followed byheating to a temperature sufficient to melt the binder.
 8. The method ofclaim 1, wherein the build powder is iron powder, the support powder issilicon dioxide powder, and the binder is a molten iron-carbon alloy. 9.The method of claim 1, wherein the build powder is copper, the supportpowder is silicon dioxide powder, and the binder is molten copper alloy.10. The method of claim 1, wherein said step of dispensing said buildpowder and said support powder in a sequence of layers is performed byan apparatus for making three-dimensional physical objects, comprising:(a) a frame; (b) a container; (c) a build powder pourer, at leastpartially filled with build powder and a support powder pourer at leastpartially filled with support powder, each of said pourers having adispensing opening and a dispensing plug, controllably covering saiddispensing opening; and (d) a pourer-movement and dispensingplug-actuating assembly supported by said frame over said container, andincluding a movement element that is selectively attachable to saidbuild powder pourer and alternately to said support powder pourer andalso capable to controllably move an attached pourer in three orthogonaldimensions and to control said dispensing plug; (e) and at least onedocking station for holding a first one of said pourers, while a secondone of said pourers is attached to said movement element; and (f) acomputing assembly, including an input for receiving a targetthree-dimensional shape, and controlling said pourer-movement anddispensing plug-actuating assembly to move said pourers and selectivelyopen said plugs, thereby causing powder to be poured into saidcontainer, and to thereby create in said container a sequence of layersof build powder patterned with support powder that collectively formsaid target shape in build powder.
 11. The method of claim 10, whereinsaid apparatus further includes a first refill tank and at least asecond refill tank, and wherein said first and second refill tanks aredisposed to dispense powder into a pourer that is held by said at leastone docking station, and wherein said first refill tank contains buildpowder and said second refill tank contains support powder.
 12. Themethod of claim 10, wherein said build powder pourer is a first buildpowder pourer and wherein said apparatus further comprises a secondbuild powder pourer, wherein said first build powder pourer is a finepourer with a first sized opening, and said second build powder poureris a fast pourer with a second sized opening that is larger than saidfirst opening.
 13. The method of claim 12, wherein said apparatusfurther comprises a third build powder pourer with an opening that is athird size that is larger than said second sized opening.
 14. The methodof claim 11, wherein said apparatus further includes a refill tank foreach pourer.
 15. The method of claim 10, wherein said pourers eachincludes a plug rod; and said pourer movement and dispensing plugactuating assembly includes a plug rod actuator that moves said plug rodvertically to open and close said opening.
 16. The method of claim 15,wherein said plug rod actuator includes an electric motor for providingthe force to lift said plug rod.
 17. The method of claim 16, whereinsaid plug rod actuator, also periodically rotates said plug rod.
 18. Themethod of claim 10, wherein said support powder pourer is a firstsupport powder pourer and wherein said apparatus further comprises asecond support powder pourer, wherein said first support powder poureris a fine pourer with a first sized opening, and said second supportpowder pourer is a fast pourer with a second sized opening that islarger than said first opening.
 19. The method of claim 18, wherein saidapparatus further comprises a third support powder pourer with anopening that is a third size that is larger than said second sizedopening.
 20. The method of claim 10, wherein said movement elementincludes a horizontal fork that is moved into engagement with a saidpourer to engage said movement element with said pourer.